The present invention relates generally to an exposure apparatus and method, and more particularly to optimizations of both an exposure condition and a reticle (or mask) pattern for an exposure apparatus. The present invention is suitable, for example, for optimizations of both the exposure condition and reticle pattern for an exposure apparatus that includes a projection optical system having a numerical aperture (“NA”) of 0.8 or greater.
A projection exposure apparatus already uses a projection optical system to expose a reticle pattern onto a wafer etc., and is increasingly required for a high resolution. A high NA of the projection optical system is effective to the high resolution, but the optimizations of both the exposure condition and the reticle pattern are also important. A reticle pattern is optimized, for example, through an optical proximity correction (“OPC”). It seems efficient to use an imaging simulation or simulator for optimization instead of exposure process. See, for example, Japanese Patent Applications, Publication Nos. 2002-319539, 2002-324752, 06-120119, 08-335552 and 2002-184688.
As the high NA scheme advances for a high resolution, the polarization's influence on an imaging characteristic increases. In particular, an imaging patterns can not print in some case depending upon a light's polarization direction in the recently proposed immersion exposure. See, for example, Proceedings of SPIE, Vol. 5377 (2004), p. 68.
The conventional optimizations of the exposure condition and the reticle pattern cannot secure a expected printing characteristic with a high NA. As a result of studies of the cause, the instant inventors have discovered that the conventional optimization does not consider a polarization dependency of an optical system, which will be simply referred to as a “polarization property” hereinafter. Information relating to the polarization property will be sometimes referred to as “polarization information.”
Due to the glass material's birefringence and birefringence in-pupil distribution, a polarization property of an actual optical system offsets from a originally designed polarization property. This offset influence is non-negligible at a high NA. The characteristic includes, for example, a polarization state of the light that passes the optical system and a pupil transmittance distribution of a projection optical system. The latter depends upon a transmittance difference among optical elements and antireflection coatings applied on their surfaces due to the high NA. The way of correcting any offset from a desired polarization property has not yet been known. As a result, there is a problem that the expected image performance cannot be achieved.